Myrhyff  of Undvik is the Ice Giant that Geralt of Rivia meets during The Witcher 3: Wild Hunt. He is a huge monster, who reigns the landmark of, since his arrival abandoned Undvik. The Ice giant fashions himself a basic protective armor made using the remains of shipwrecks.
Geralt is asked by a jarl Crach of Clan an Craite to find his son Hjalmar who had earlier left on a personal quest to find and kill the creature. For this, the witcher crosses the sea, and employs himself with Witcher Senses to track young an Craite and his friends.
The trail leads Geralt to the cave of an Ice giant where one of Hjalmar's crew, Vigi known as the Loon, is being held captive. Geralt must decide whether or not to kill the giant in his sleep, or fight him "honorable way".
- If you are interested in how to defeat creature than see combat tactics.